1. Field of the Invention
This invention relates to and has an object provision of novel materials having fibronectin-like activity, which are suitable for use as sources of fibronectin and as fibronectin substitutes and novel methods of making these materials.
2. Description of the Prior Art
The therapeutic value of fibronectin has been recognized by a number of workers. Fibronectin plays an important role in cellular adhesion, malignant transformation, reticuloendothelial system function, and embryonic differentiation (Yamada et al., Nature, 1978, Vol. 275, pages 179-184; Saba, Ann. Surg., August 1978, pages 142-152; Scovill et al., The Journal of Trauma, 1976, Vol. 16, No. 11, pages 898-904); and Scovill et al., Ann. Surg., October 1978, pages 521-529.
The fractionation of human blood plasma to produce an antihemophilic factor (AHF) concentrate (Factor VIII) is known: Hershgold et al., J. Lab. Clin. Med., 1966, Vol. 67, pages 23-32 and U.S. Pat. Nos. 3,973,002 and 4,170,639, hereinafter '002 and '639, respectively. In the Hershgold and '002 processes cryoprecipitate is recovered from thawed pools of fresh frozen human plasma at a temperature of about 2.degree.-10.degree. C. by centrifugation and dried and washed to remove soluble proteins, then, the cryoprecipitate is extracted with an aqueous buffer, and the pH of the extract is adjusted to about 6.5-7.5. The so-adjusted aqueous extract of AHF proteins is purified by contact with aluminum hydroxide. After purification the aqueous AHF extract is constituted with buffer and saline, and its pH is adjusted to within the range 6.50-6.95. The so-adjusted solution is freeze-dried to yield solid AHF concentrate.
In the '002 process cryoprecipitate is extracted in aqueous buffer, and the extract is purified by contact with aluminum hydroxide as described above. The purified extract is adjusted to pH 6.0-7.0 by addition of acid and then chilled to 2.degree.-20.degree. C. for a period of about 15-60 minutes. After centrifugation, the residue is discarded and the supernatant is treated as described above to obtain a solid AHF concentrate.
In the manufacture of an AHF concentrate, therefore, cryoprecipitate is solubilized in an aqueous medium and, the solution is acidified to pH 6.0-7.0 by the addition of a biologically-acceptable acid as known in the art. The solution then is chilled to a temperature of about 2.degree.-20.degree. C. and centrifuged. The supernatant is separated from a residue, called the acid-chill precipitate, which is discarded, and is treated with aluminum hydroxide to purify it. An AHF concentrate is recovered from the so-purified supernatant according to the known procedure outlined above, i.e., constitution of the supernatant with buffer, saline, and acid and freeze-drying the supernatant.